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Can you activate a velocity motion mid-analysis without resetting the position of the assembly?

jsph_inc
Hi All,
 
I'm a bit stuck.
 
I'm trying to setup a simulation where in the first phase, the assembly settles to a position under the summation of external forces (its velocity settles to zero with a certain displacement).
 
In the second phase, I'd like to apply a velocity motion at its settled position. I'm trying to do this by activating a velocity motion (with initial velocity of zero) through a script after a certain time. However, when the velocity motion gets activated the assembly is instantaneously moved to it's initial position and the simulation dies.
 
Is there a way to activate a velocity motion and not affect the position of the assembly at the instant the motion is activated?
 
thanks,
joe.
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  • 0
    Hi Joe,
    this is rather trivial. You only have to move one of the markers for the joint where the motion is applied to coincide with the other one.
    So assume that you have a MOTION/1, applied as a rotation around a JOINT/1. The two markers that is sued to define JOINT/1 is caller MARKER/42 and MARKER/43.
    Now you script snippet will look like
     
    deactivate/MOTION,id=1
    sim/dyn,end=1,dtout=0.01 ! settle phase
    marker/43, QP=0,0,0, REUL=0,0,0, RM=42 ! This moves and rotates marker 43 to coincide with marker 42
    activate/MOTION,id=1 ! As long as the motion has 0 start position.
     
     
     
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  • 0
    Hi Joe,
    this is rather trivial. You only have to move one of the markers for the joint where the motion is applied to coincide with the other one.
    So assume that you have a MOTION/1, applied as a rotation around a JOINT/1. The two markers that is sued to define JOINT/1 is caller MARKER/42 and MARKER/43.
    Now you script snippet will look like
     
    deactivate/MOTION,id=1
    sim/dyn,end=1,dtout=0.01 ! settle phase
    marker/43, QP=0,0,0, REUL=0,0,0, RM=42 ! This moves and rotates marker 43 to coincide with marker 42
    activate/MOTION,id=1 ! As long as the motion has 0 start position.
     
     
     
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